1. Field of the Invention
This invention relates to a system and method of providing FDD and TDD modes of operation for a wireless communications device.
2. Discussion of Related Technology
Many wireless telephones today utilize only a time division duplex (TDD) mode of operation. In a typical TDD operation, a wireless telephone unit and a base unit each transmit for about one millisecond and receive for about one millisecond, thereby sharing the same radio channel. This presents certain disadvantages, for example, in TDD, communication must be at a higher bit rate since a transmitter and receiver are on the same channel. Communication cannot be continuous, since transmit and receive modes have interleaved time slots preassigned. Also, the higher bit rate implies lower energy, so the bit energy to noise ratio is worse than for a frequency division duplex (FDD) mode of operation. The increased noise ratio shortens the useful range of a TDD system.
Thus, the need arises for a wireless communications system which provides operation in both the TDD mode and the FDD mode, allowing for higher energy operation, with increased range and continuous operation over different channels for receive and transmit.